The present invention relates to a system for controlling the ignition timing of an internal combustion engine such as an automotive engine.
A learning control system for correcting the ignition timing has been proposed. The control system is adapted to advance the ignition timing so as to produce a maximum torque as long as the level of the engine knock does not exceed a tolerable level. The ignition timing is stored in a RAM and corrected in accordance with engine operating conditions. If the ignition timing is largely corrected in transient state, it takes a long time to converge the deviated ignition timing to a desired timing in steady state, or large variation occurs in engine torque, which will cause the decrease of driveability of a motor vehicle. Further, if the gasoline for the engine is changed to another kind of gasoline having different octane value, the ignition timing must be properly corrected.